Evaluation of the interactions between collagen and the surface of a bioactive glass during in vitro test

Interactions between biomaterials and the body environment usually determine the lifetime and performance of biomedical devices used as implants. Among a variety of different types of interactions that occur whenever biomaterials are implanted into the body, adsorption of biomacromolcules onto the surface of biomaterials can guide other relevant processes such as cell attachment, cell differentiation, cell proliferation, tissue growth and biomaterials degradation. In this work, fundamental mechanisms associated with the interactions between collagen and the surface of biomaterials were studied by using Atomic Force Microscopy (AFM). The ultimate goal of this work is to isolate and simulate phenomena occurring at the molecular level, when biological entities are brought in contact with biomaterials. These results can then be used to design and test new biomedical devices. This manuscript reports the evaluation of interactions between collagen and the surface of bioactive glasses. These bioactive glasses are known to bond to soft and hard tissues through the formation of a hydroxy-carbonate-apatite layer. Collagen was grafted onto AFM cantilevers. AFM force-displacement curves were obtained using these modified tips against the surface of a bioactive glass at different stages of an in vitro test performed in a simulated body fluid. The results showed that the structure of the bioactive glass surface affects the adsorption of collagen on the biomaterial. The magnitude of the adhesion force measured is highly dependent on the deposition of a hydroxyl-carbonate-apatite at the surface of the glass.